If you need a way to charge your gadgets on the go and you're not particularly fond of also having to charge a battery, let the sun do half of the work for you. Instructables user andrea biffi demonstrates how it's not that hard to make your own solar USB battery with four ports.

The project isn't as hard as you'd think. All you really need are some solar panels (his full post details your many options), rechargeable batteries, a controller board, wires, and a few applicable tools. While certainly not a novice project, the steps aren't that complicated. It is, for the most part, just assembling things in the right order. If you're looking for a fun, useful, and relatively inexpensive project to tackle, this is one to check out.